A known friction stir welding machine provided with a welding tool is used for carrying out a method of welding plural workpieces together.
FIG. 17 is a typical perspective view of a moving table type friction stir welding machine 1. The friction stir welding machine 1 includes a welding tool 2, a work table for supporting workpieces 3 thereon, and a base 5 on which the work table 4 is moved unidirectionally. The work table 4 supporting the workpieces 3 thereon is moved in a moving direction indicated by the arrow 6. The welding tool 2 can be moved toward and away from the work table 4. The rotating welding tool 2 is pressed against the workpieces 3 and the joint of the workpieces 3 extending along a weld line is welded by friction stir welding as the workpieces 3 are moved in the moving direction.
FIG. 18 is a typical perspective view of a gantry type friction stir welding machine 7. The friction stir welding machine 7 includes a welding tool 8, a work table 10 for supporting workpieces 9, a support structure 11 supporting the welding tool 8, and guide rails 12 for guiding the support structure for movement in a welding direction. The gantry type friction stir welding machine 7 differs from the moving table type friction stir welding machine 1 in that the work table 10 supporting the workpieces 3 is stationary, and the support structure 11 supporting the welding tool 8 moves in a moving direction indicated by the arrow 13 in FIG. 18. The welding tool 8 can be moved toward and away from the work table 10. The rotating welding tool 2 is pressed against the workpieces 9 and the joint of the workpieces 3 extending along a weld line is welded by friction stir welding as the welding tool 8 is moved in the moving direction.
The moving table type friction stir welding machine 1 needs to move the workpieces 3 by a distance corresponding to the length of the joint. The workpieces 3 need to be moved by a distance at least twice the length of the joint. When the workpieces 3 have a length of, for example, 20 m, the length of the base 5 of the moving table type friction stir welding machine 1 needs to be 40 m or above. The moving table type friction stir welding machine 1 having the base 5 of such a long length is large and requires a large space for installation. Similarly, the welding tool 8 of the gantry type friction stir welding machine 7 needs to be moved by a distance corresponding to the length of the joint and needs the guide rails 12 having at least a length equal to the length of the joint. Thus, the gantry type friction stir welding machine 7 is large and requires a large space for installation.
FIG. 19 is a typical perspective view of a known self-propelled friction stir welding machine 15 formed in a small size by a conventional, technique. The self-propelled friction stir welding machine 15 includes a welding tool 16 and a vehicle 17 capable of carrying the welding tool 16. The vehicle 17 has four wheels 18. The wheels 18 are rotated to propel the self-propelled friction stir welding machine 15 for traveling in a traveling direction indicated by the arrow 21 shown in FIG. 19 on the surfaces of workpieces 20 placed on a work table 19. The self-propelled friction stir welding machine 15 presses the rotating welding tool 16 against the workpieces 20 while traveling in the traveling direction to weld the joint of the workpieces 20 by friction stir welding. The size of the self-propelled friction stir welding machine 15, unlike those of the foregoing moving table type and the gantry type friction stir welding machine, is not dependent on the size of the workpieces 3 and the self-propelled friction stir welding machine 15 can be formed in a small size as mentioned in, for example, Patent documents 1 and 2.
Patent document 1: JP 2005-186084 A
Patent document 2: JP 2007-876 A